This invention relates to a marine drive with a spider differential assembly, and more particularly to such an assembly for use in a dual propeller drive.
Previously known devices of the type under consideration here provide dual propellers for driving a boat through the water. The propellers have normally been of reversed configuration, but otherwise identical, and have been rotatable about a common axis and disposed closely adjacent each other. Using two propellers reduces vibration, increases thrust, and essentially eliminates reverse torque effective from the drive on the boat.
Examples of such known drives are disclosed in U.S. Pat. Nos. 2,229,153 and 4,540,369.
The prior known drives have required that the parts involved be machined with a high degree of precision, which makes them costly to manufacture.
It is an object of the present invention to provide a dual propeller marine drive differential assembly wherein a number of the parts thereof need not be machined to extremely close tolerances, and yet the torque between the spider gears of the assembly is accurately divided.
In accordance with the various aspects of the invention, a spider differential assembly of a marine drive is constructed so that the spider and its associated spider pinion gears can float in all directions, except about the common central axis of the propeller drive shafts. More particularly, a spider is provided with a central hub opening through which the main drive shaft passes. A plurality of radially extending spindles carry the spider gears and extend outwardly where they terminate in an enclosure arranged to prevent circumferential spider movement about the common drive shaft axis, but which permits free spider floating.